The ultimate goal of mobile broadband should be the ubiquitous and sustainable provision of non-limiting data rates to everyone and everything at every time. Along this path, millimeter network (mmW) may be an important next step following the successful introduction of LTE (Long Term Evolution, a telecommunication standard of the 4th generation) for wide-area and local-area access. Even though only a local-area access technology, MMW can be deployed in areas with high traffic improving throughput. Through overprovision and the related low average loads in the access network, MMW could create ubiquitous access opportunities which—even under realistic assumption on user density and traffic—provide users with all desired data rates.
Overprovision can be achieved by an extremely dense grid of access nodes; inter-access-node distances in the order of tens of meters and below are envisioned, in indoor deployments one or even multiple access nodes are conceivable in each room. Additionally to increased network capacity, densification—via reduced transmit powers—also offers access to vast spectral ranges in the millimeter-wave bands and thus increased data rates.
For example, several GHz of spectrum is available in the unlimited 60 GHz band and potentially more in other millimeter-wave bands, for which multi-Gb/s transmissions are possible even with technologies providing moderate spectral efficiency. Schemes with moderate spectral efficiencies offer robustness and energy efficient data transmission. Furthermore, there are also implementation issues at higher millimeter-wave frequencies that make it very challenging to provide very high spectral efficiency (in b/s/Hz). In this sense, one can trade spectral efficiency for bandwidth. Generally, mmW technology comes with a set of issues which are not suitable to be solved with current LTE technology.